alt Hacker News> what's the meaningful distinction now?
SBC is a PCB which includes ports for power, I/O, often other parts like sensors on it. Esp32 is a MCU. You can put an Esp32 on a PCB and call it an SBC. (Although semantically SBC usually refers to something that runs a GPOS, but perhaps that's flexible or changing)
It's much more difficult to buy the ESP32 as an MCU than it is to buy it as a SBC, with ports for power and I/O already on a PCB (often with through pins, to land on another PCB, like the arduino hats). And I don't mean "it's difficult because you have to solder" - I mean "it's difficult to find many places that sell it".
Ex - go check amazon, they're all the "dev kit" versions of ESP32.
Hell - even Alibaba has an overwhelming majority of the kits in the SBC form, rather than the straight MCU (although they at least exist in that form there, unlike amazon).
Even on digikey... there are like 4 listing for the straight MCU, and hundreds of listings for PCB board versions.
So I think for most consumers purchasing these... functionally they end up buying a form factor that is much closer to SBC than MCU.
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From my perspective... I'm old enough to remember when Arduinos were the hot shit in this space, and now ESP32 is basically the same value prop at 1/10 the price point (or better, if you are actually willing to solder it to the PCB yourself... then you get down to 1/50th the price point).